Signal modifier for fuel injection system



Nov. 24, 1959 5 Sheets-Sheet 1 Filed May 9, 1957 aff? IN VEN TORS J/f?90/ A Trop/wry Nov. 24, 1959 J. DoLzA ETAL 2,914,051

SIGNAL MODIFIER FOR FUEL INJECTION SYSTEM Filed May 9, 1957 3Sheets-Sheet 2 'ff @y NUV- 24, 1959 J. DoLzA ErAL v2,914,051

SIGNAL MODIFIER FOR FUEL INJECTION SYSTEM Filed May 9, 1957 3Sheets-Sheet 3 IN V EN TORS A TTOR/VEY SIGNAL MODIFIER FOR FUELINJECTION SYSTEM John Dolza, Fenton, and William H. Kolbe, HuntingtonWoods, Mich., assignors to General Motors Corporation, Detroit, Mich., acorporation of Delaware Application May-9, 1957, Serial No. 658,091

6 Claims. (Cl. 12S- 119) The present invention relates to a fuel:injection system of the mass `air flow type as generally shown incopending application Serial No. 608,853 Dolza, filed September 10,1956, now Patent No. 2,843,098. In particular, the present devicerepresents an improvement over the earlier Dolza system in providing anovel cold enrichment mechanism. In lthe earlier Dolza system a solenoidmechanism was provided which retained the fuel metering valve in Iamaximum flow position for a timed interval to obtain an enrichedstarting mixture. Such control results in a step type enrichment whichapproximates but does not reflect the actual needs of the engine.

In the present system a device is provided whereby a modulatedenrichment of the system is achieved and which enrichment is accuratelydetermined by the needs of the engine during warm up. In the presentdevice the modulated enrichment is achieved by providing a meteringsignal modifying valve which is controlled by temperature and air flowin such a wayas to vary the metering vacuum signal in inverse proportionto such temperature and air flow. t

In the present invention the signal modifier valve is mounted in the airintake or induction passage anteriorly of the venturi and is offset withrespect to the induction passage so as to be responsive to the air owtherethrough and is further connected with a thermostatic element whichtends to close said valve with a force inversely proportional totemperature. The present signal modifier valve is adapted to coact withthe venturi so as to provide a fuel metering control force which isproportional to the quantity of air flowing through theventuri and thedegree to which said valve is closed.

2,914,051 Patented Nov. 24, 1.959

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The details as well as other objects and advantages of the presentinvention are set forth in the description which follows.

In the drawings:

Figure 1 is a partially sectioned view of a fuel injection systemembodying the subject invention;

Figures 2, 2a and 2b are enlarged views showing the subject invention ingreater detail; and Y Figures 3 and 4 represent a modified form of thesubject invention.

Except as will hereinafter be specifically pointed out, the present fuelinjection system functions in the same manner as in the aforenotedcopending Dolza application.

` Brieiiy, the fuel injection system includes an intake casing 10 havingan air induction passage 12 formed therethrough. The induction passage12 includes a tapered plug 13 disposed therein which coacts with thecasing 10 to define an annular venturi 14. A throttle valve 16 is alsodisposed in the induction passage 12 posteriorly to venturi 14. Theinduction passage communicates with an air manifold or plenum chamber18'from which the l air is supplied to the individual cylinders of theengine through intake passages 20. Fuel under pressure is supplied froma source 21 to a valve member indicated generally at 22 Where the fuelis metered through the action of a diaphragm .controlled Avlinkagemechanism24. .The

which communicate with the individual cylinder intake passages 20 andeach of which conduits terminates in a nozzle member 28. In this way thefuel and air are adapted to be mixed just prior to their induction intothe engine cylinders 30.

Metering valve control mechanism 24 includes a diaphragm 32 having avacuum chamber 34 which com-v municates with venturi 14 through aconduit 36 and an annular open venturi chamber 38. The diaphragm 32 alsoincludes another chamber 40 which is vented to the atmosphere through aconduit 42 within the induction passage 12 anteriorly of the venturi 14.

As already noted, in the earlier Dolza application a solenoid wasprovided for retaining the meteringfvalve 22 in a maximum fuel outputposition to provide cold starting enrichment. The solenoid typeenrichment control represents an approximation of engine needs and whichcold starting and running enrichment control is considerably refined bythe mechanism now to be described.

The theory of the present device has been to provide a mechanism wherebythe metering control force acting on diaphragm 32 is reinforced orsupplemented in inverse proportion to engine air flow land temperature.In this way when the engine is coldest a maximum metering signal will begenerated and will retain the metering valve 22 in its maximum fueloutput position. The reinforcing of the metering signal willprogressively diminish or be modulated as the engine warms and becomescapable of running on a leaner fuel-air mixture.

To this end, and as shown in Figures l and 2, a signal modifying valve50 is disposed in an extended intake casing portion 52 upon which an aircleaner 54 is adapted to be mounted. As better seen in Figures 2a and2b, the

`modifyingvalve 50 is mounted on a shaft 56 which is offset with respectto the intake passage so that the valve is unbalanced and hence'responsive to air flow tending to open as such oW increases. In order,under cold starting conditions particularly, to supplement the meteringcontrol signal which is normally generated in venturi chamber 38 by airfiow therepast, it is necessary to maintain the valve 50 in a closedposition. In this way manifold depression will create a high vacuumforce posteriorly of the modifier valve 50 and in so doing increase thevacuum force in vacuum chamber 38.

T o maintain the modifier valve in a closed position and to open thesame as the engine warms, a temperature responsive mechanism indicatedgenerally at 58 is provided. The temperature responsive mechanismincludes a bimetalliccoil e1ementv60 adapted to be anchored at one end62 to the induction casing and fixed at its other end to the modifiervalve shaft 56. Thermostatic coil 60 is so arranged that the force withwhich it retains the valve 50 in a closed position varies inversely withtemperature.,

It is also desirable to make the modier valve 50 responsive to engineload which is manifested by the magnitude manifold vacuum. To this end,a vacuum piston 64 is mounted in a bore 66 formed in the casing 68 ofthe thermostatic mechanism 58. Piston 64 is suitably articulated to themodifier valve shaft 56 through a link 70 and a lever 72 fixed to theshaft. A conduit 74 is adapted to communicate manifold vacuum to the endof the vacuum piston 64 so as to urge the latter in a valve openingdirection as manifold vacuum increases to indicate a decrease in engineload.

As thus far described the signal modifier valve is made responsive tothree engine operating conditions, namely, engine temperature throughbimetallic member 60, engine demand through the offset or unbalanceconstruction of Valve 50 and engine load through vacuum piston 64.

If it should be desired to tailor the operation of the signal modifiervalve for a particular type of stepped operation, it is possible toprovide a passage 76 in the vacuum piston 64 which is adapted to bleeddown to re-A duce the effectiveness of manifold vacuum on the pistonduring certain phases of engine operation. A conduit 78 is formed incasing 68 and communicates with piston bore 66 and the thermostaticchamber 80, the latter which may be maintained at atmospheric pressureor, as will subsequently be considered, may be in communication with astove or heating mechanism. Under certain operating conditions conduit78 is adapted to be communicated with conduit 76 in vacuum piston 64 aswill be seen from a description of the operation of the device whichfollows.

With the engine cold and hence requiring an enriched fuel-air mixturethermostatic element 60 will retain the modifier valve 50 in its closedposition as shown in Figure 2. ln such position a maximum meteringsignal will be transmitted through venturi chamber 38 and conduit 36 todiaphragm chamber 34 which will position the metering valve 22 in amaximum fuel flow condition. After the engine begins to fire manifoldvacuum will shift the vacuum piston 64 to the position shown in Figure2a in which the signal modifier valve is partially opened and also inwhich position piston conduit 76 communicates with conduit 78 to bleeddown the manifold vacuum force acting on the piston. This will cause themodifier valve 50 to be retained in the partially opened position untilsuch time as the engine warms sufficiently to permit the thermostaticcoil member 60 to relax and open the valve sufficiently more to move thevacuum piston 64 to interrupt the registry between conduits 76 and 78permitting manifold vacuum to again urge the valve to a still furtheropen position.

In order that the final amount of opening of the modifier valve 50 beunder the control of the thermostatic coil member 60 a lost motion pinand slot connection 82 and 84 is formed between lever 72 and link 70 sothat after manifold vacuum causes the piston 64 to bottom within thecasing bore 66 as shown in Figure 2b, the bimetallic coil will completethe final opening of the valve.

If it is desired to make the coil 60 more accurately responsive toengine temperature, it is possible, as suggested above, to communicatethe thermostatic chamber 80 with a source of engine heat such as theexhaust manifold. In this event the manifold vacuum acting on vacuumpiston 64 will draw such heated air across the thermostatic member whenconduits 76 and 78 are in registry. It is apparent that, if such isdesired, the device may be modified to continuously draw heated airthrough chamber 80.

If it is preferable to eliminate the stepped type control of the airvalve which is achieved by providing the conduits 76 and 78, it ispossible to eliminate the latter conduits whereby manifold vacuum willcontinuously act on the piston 64 to provide an even engine loadmodulation of the action of the thermostatic element 60.

During cold starting and cold running operation engine friction ishigher than during warm engine operation. For this reason it is normalpractice to provide means for supplying a greater charge to the enginewhen the latter is cold than when it is warm. For this purpose a fastidle cam member 86 is mounted on the induction casing 52. Cam 86includes a stepped cam surface 88 with which an adjustable screw member90 mounted on a lever 92 fixed to the throttle shaft 94 can coact toregulate the quantity of air which flows past the throttle 16 underidling conditions. Thus as engine temperature increases, the fast idlecam is adapted to be rotated in a clockwise direction, as viewed inFigure 2, causing the screw 90 to progressively engage lower steps ofthe cam and reduce the engine idling speed. The rotation of the fastidle cam 86 is adapted to be controlled by the thermostatic element 60to which it is articulated through a suitable link 96 and lever 98.

If it is desired to reduce the longitudinal displacement or length ofthe induction passage casing, it is possible to utilize a pair of signalmodifying valves and 102 as shown in the modification of Figures 3 and4. In this event, the individual valves 100 and 102 are mounted onseparate shafts 104 and 106 and have unbalanced areas in order to be airfiow responsive as in the modification of Figures 1 and 2.

Further, if it is desired for better heat response or other reasons tomount the thermostatic controlling mechanism other than on themodulating valve shaft 56, as shown in Figures l and 2, it is possibleto position this mechanism 58' elsewhere, as shown in Figure 3. In thiscase the mechanism 58 is connected through suitable levers and links108, 110, 112, 114 and 116 to the signal modifying valve shafts 104 and106. -In the case of the modification of Figure 3, a link 118articulated between the thermostat lever 120 and fast idle cam 86determines the idle position of throttle shaft 94.

It is apparent that various modifications may be made in the presentdevice within the scope of the invention as set forth in the appendedclaims.

We claim:

l. A fuel injection system for an internal combustion engine comprisingan air induction passage, an annular venturi means disposed in saidinduction passage, a throttle valve in said induction passageposteriorly of said venturi means, a plurality of intake passagescommunicating the induction passage with the individual cylinders ofsaid engine, a source of fuel under pressure, conduit means forcommunicating said fuel source with the intake passages, a meteringvalve intermediate said fuel source and said conduit means, diaphragmmeans for actuating said metering valve, an annular chamber formed insaid induction passage and communicating with said venturi means, aconduit communicating said chamber with said diaphragm means forincreasing the flow through said metering valve with an increase in airflow through said venturi, air fiow responsive valve means disposed insaid induction passage anteriorly of said venturi means, a temperatureresponsive member operatively connected to said air fiow responsivevalve means for resiliently holding said valve means in a closedposition to increase the vacuum force in said induction passage chamberwhereby said metering valve will insure an enriched fuel-air mixturewhen the engine is cold, said temperature responsive member beingadapted to open said air fiow valve as the engine warms, and engine loadresponsive means for modifying the operation of the temperatureresponsive member.

2. A fuel injection system for an internal combustion engine comprisingan air induction passage, an annular venturi means disposed in saidinduction passage, a throttle valve in said induction passageposteriorly of said venturi means, a plurality of intake passagescommunicating the induction passage with the individual cylinders ofsaid engine, a source of fuel under pressure, conduit means forcommunicating said fuel source with the intake passages, a meteringvalve intermediate said fuel source and said conduit means, diaphragmmeans for actuating said metering valve, an annular chamber formed insaid induction passage and communicating with said venturi means, aconduit communicating said chamber with said diaphragm means forincreasing the flow through said metering valve with an increase in airow through said venturi, air flow responsive valve means disposed insaid induction passage anteriorly of said venturi means, a temperatureresponsive member operatively connected to said air fiow responsivevalve means for resiliently holding said valve means in a closedposition to increase the vacuum force in said induction passage chamberwhereby said metering valve will insure an enriched fuel-air mixturewhen the engine is cold, said temperature responsive member beingadapted to open said air flow valve as the engine warms, and manifoldvacuum responsive means operatively connected to said air flow valve forurging said valve in an open direction as manifold vacuum increases.

3. A fuel injection system for an internal combustion engine comprisingan air induction passage, an annular venturi means disposed in saidinduction passage, a throttle valve in said induction passageposteriorly of said venturi means, a plurality of intake passagescommunicating the induction passage with the individual cylinders ofsaid engine, a source of fuel under pressure, conduit means forcommunicating said fuel source with the intake passages, a meteringvalve intermediate said fuel source and said conduit means, diaphragmmeans for actuating said metering Valve, an annular chamber formed insaid induction passage and communicating with said venturi means, aconduit communicating said chamber with said diaphragm means forincreasing the ow through said metering valve with an increase in air owthrough said venturi, air ow responsive valve means fixed for rotationon a shaft in said induction passage anteriorly of said venturi means, abimetallic temperature responsive coil concentrically disposed about andfixed at one end to said shaft, said coil xed against movement at itsother end for resiliently holding said valve means in a closed positionagainst the force of air ow to increase the vacuum force in saidinduction passage chamber whereby said metering valve will insure anenriched fuel-air mixture when the engine is cold, said coil beingadapted to open said airflow valve as the engine warms, a piston mountedon the induction passage and articulably connected to the air ow valveshaft, and conduit means communicating manifold vacuum with said pistonto urge the air ow valve in an open direction as engine load decreases.Y

4. A fuel injection system as set forth in claim 3 in which said vacuumpiston is connected through a lost motion mechanism to the air ow valveshaft whereby under certain operating conditions manifold vacuum isinoperative to eifect the position of said valve.

5. A fuel injection system for an internal combustion sagescommunicating the induction passage with the individual cylinders of theengine, -a source of fluid under pressure, conduit means communicatingsaid fuel source with the individual intake passages, valve means formetering the quantity of fuel flow through said conduit means, diaphragmmeans for controlling the actuation of said valve, `a venturi in saidinduction passage, a conduit communicating with said venturi and saiddiaphragm means whereby said latter means is actuated to increase theoutput of said metering valve in proportion tothe mass of air flowthrough said venturi, a throttle valve dis posed in said inductionpassage posteriorly of said venturi, and valve means disposed in saidinduction passage anteriorly of said venturi for modifying thediaphragmmetering control force in accordance with certain engine operatingconditions.

6. A fuel injection system for an internal combustion engine comprisingan air induction passage, intake passages communicating the inductionpassage with the individual cylinders of the engine, a source of fluidunder pressure, conduit means communicating said fuel source with theindividual intake passages, valve means for metering the quantity offuel ow through said conduit means, diaphragm means for controlling theactuation of said valve, a venturi in said induction passage, a conduitcommunicating with said venturi and said diaphragm means whereby saidlatter means is actuated to increase the output of said metering valvein proportion to the mass of air ow through said venturi, a throttlevalve disposed in said induction passage posteriorly of said venturi,and valve means disposed in said induction passage anteriorly of saidventuri for modifying the diaphragm metering control force in accordancewith certain engine operating conditions, a cam for limiting the idleposition of the throttle valve and means connecting said valve means andcam whereby the position of said cam is determined by the position ofsaid valve means.

References Cited in the le of this patent UNITED STATES PATENTS2,785,669 Armstrong Mar. 19, 1957

